Will we soon have flying carpets? Skyscrapers without elevators? Airplanes without wings?
We should start to think seriously about such fantasies, because science is beginning to understand gravity, which is not only the most familiar force but also the most mysterious one. The most famous scientists in history, Isaac Newton and Albert Einstein, built their fame and reputation on mathematical models for gravity. And thanks to their revolutionary work, we can understand the actions of gravity, we can calculate these actions and we can even predict their effects many years in advance and over distances of millions of miles. And yet, no-one really knows or understands what gravity is or how it works. And attempts to find direct proof of its existence have failed, in spite of colossal experiments to detect the “gravity waves” that are predicted by Einstein’s General Theory of Relativity.
But more and more scientists are now questioning gravity, because they can no longer explain the latest observations of the behavior and the structure of the universe.
One problem is that the universe expands faster than it should, according to the laws of gravity. On a cosmic scale the attraction of gravity seems weaker than expected, which is attributed to a mysterious and invisible “dark energy” that counter-acts gravity.
Another problem is that science cannot explain the structure of the universe. The matter that we see in the universe can be no more than 15 percent of what must really be there. So 85 percent of all matter in the universe seems lost or missing, but the gravitational effects are undeniably there, so also this matter must be invisible or “dark.” We live in a universe that is filled with energy and matter that we cannot see; a very unsatisfactory situation.
The first who put the cat among the pigeons, was the Dutch theoretical physicist Erik Verlinde (University of Amsterdam). In 2010 he concluded in a groundbreaking article that Einstein’s General Theory of Relativity should be abandoned. Gravity itself is not a force of nature or a property of space-time, but it ’emerges’ from other forces of nature. Similar ideas had been proposed by others, like the Russian physicist Andrej Saccharov (1921-1989) and even Edgar Allan Poe (1809-1849) in his amazing cosmogony ‘Eureka’ (1848). But Verlinde also expressed his idea in surprisingly simple and elegant mathematics, which gave it much credibility. Other scientists followed with different arguments that a new concept of gravity will be necessary to understand the universe.
Verlinde’s article was a bombshell in the scientific world, although it did not explain the anomalies in the universe. However, if we really can understand how gravity emerges from other forces, it may also be possible to manipulate it and, maybe, even shield or neutralize it. That would revolutionize our daily life. Just imagine that gravity can be switched on and off, like electricity. Even the sky is no limit for such new and amazing possibilities.
Another important characteristic of gravity has come under scrutiny too, namely its velocity. Isaac Newton believed that gravity acts instantaneously through space, although in his mathematics that did not really matter. Gravitation is there and it works, so its velocity is not important. But according to Einstein’s General Theory of Relativity gravity has the velocity of light. However, if gravity is an effect that emerges from other, “deeper” forces between particles, there is a fair chance that it has infinite velocity (‘superluminosity’), like the mysterious phenomenon of “entanglement” in quantum physics. If this is true, it will change our view on the universe. It will also explain why “gravity waves” cannot be found, simply because they do not exist.
If gravity is instantaneous, the universe must be larger than what we see. The visible universe, that contains only 15 percent of all matter, is then only a central sphere that is surrounded by an outer shell that contains 85 percent of all matter. But this matter is not visible because its light and other electromagnetic signals have not reached us yet. However, the gravitational attraction constantly influences the matter in the visible part of the universe. So “dark matter” exists, but it lies beyond our observation horizon. And its gravity pulls the matter in the visible universe radially towards the outside, thus causing an accellerated expansion or apparent “dark energy.” And although a universe with six to seven times more matter sounds really big, the radius of such a universe is less than two times the radius of the visible universe, because content is the cube of radius.
One question remains: does gravity have infinite velocity, or only the speed of light? Such a fundamental question should not be too difficult to answer, but no-one has come up with the right idea yet, although it is certainly worthy of a Nobel Prize.